Copper complexes and process for formatiom of copper-containing thin films by using the same

ABSTRACT

Copper-containing thin films can be industrially advantageously formed by chemical vapor deposition using as the copper source a divalent copper complex bearing β-diketonato ligands having silyl ether linkage. A representative example of the divalent copper complex is represented by the formula (I):  
                 
 
wherein Z is hydrogen or alkyl; X is a group represented by the formula (I-I), in which R a  is alkylene, and each of R b , R c  and R d  is alkyl; and Y is an alkyl group or a group represented by the formula (I-I), in which R a  is alkylene, and each of R b , R c  and R d  is alkyl.

FIELD OF INVENTION

The present invention relates to a copper complex which isadvantageously employable for producing a thin metal film comprisingcopper or copper alloy or a thin metal film comprising a complex metaloxide containing copper by chemical vapor deposition. The inventionfurther relates to a process for producing a thin metal film comprisingcopper or copper alloy or a thin metal film comprising a complex metaloxide containing copper from the above-mentioned copper complex.

BACKGROUND OF INVENTION

A metallic copper thin film (hereinafter simply referred to as “copperthin film”) is employable as a copper circuit of a siliconsemiconductor. A metal oxide thin film containing copper oxide(hereinafter simply referred to as “copper oxide thin film”) is expectedas material for high-critical temperature superconductors.

As the processes for producing the copper thin film or complex oxidethin film containing copper oxide by vapor deposition procedure, variousprocesses are known. A representative process is a chemical vapordeposition process (CVD process) comprising the steps of thermallydecomposing a compound containing a copper atom under specificconditions and depositing the decomposition product on a substrate toproduce thereon a copper thin film or a copper oxide thin film.

For the production of a copper thin film or a copper oxide thin film inthe CVD process, β-diketonato copper complexes are generally used.

JP-A-5-59551 describes a process for producing a copper thin film (to beused as a copper circuit of a silicon semiconductor) using aβ-diketonato copper(I) as a copper source. The β-diketonato copper(I) isadvantageously employed because it can be subjected todisproportionation reaction, to deposit metallic copper. However, it hassuch a defect that the β-diketonato copper (I) is thermally unstable,and that some of β-diketonato copper(I) decompose when these are heatedto vaporize in the CVD process.

A typical divalent β-diketonato copper complex employed in the CVDprocess is dipivaloylmethanato copper(II) complex. This copper complexis more thermally stable than the monovalent β-diketonato coppercomplex. However, since the dipivaloylmethanato copper(II) complex hassuch a high melting point as 198° C., it likely deposits in a CVD systemand plugs the production line. Other known β-diketonato copper complexesalso have the same problem. Moreover, since the dipivaloylmethanatocopper(II) complex and other known β-diketonato copper complexes have alow vapor pressure, the thin film production rate is low. Accordingly,these known β-diketonato copper complexes are not appropriate asindustrially employable copper sources.

JP-A-2001-181840 describes a β-diketonato copper(II) complex having thefollowing formula (II):

which is liquid at room temperature and solves the problems of the knownmaterial.

The above-mentioned β-diketonato copper(II) complex exists as a viscousliquid at temperature. Therefore, it is easily supplied in the CVDsystem and free from the problem of plugging. Nevertheless, it stillshows a low film production rate, and therefore, some of the problems inthe production workability are still unsolved.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a copper complexwhich has a low melting point and is thermally stable, so that it isfavorably employable as the copper source in the CVD process forproducing a copper thin film or a copper oxide thin film.

It is another object of the invention to provide a process for producinga copper-containing thin film such as a copper thin film or a copperoxide thin film in which the above-mentioned copper complex is used.

The present inventors have discovered that a copper complex havingβ-diketonato ligands containing a silyl ether linkage can solve theabove-mentioned problems. The present inventors have been complete basedon this discovery.

Accordingly, the present invention resides in a divalent copper complexhaving β-diketonato ligands containing a silyl ether linkage.

The invention also resides in a method of forming a copper-containingfilm by chemical vapor deposition using a copper(II) complex havingβ-diketonato ligands containing a silyl ether linkage as a coppersource.

As the β-diketonato ligands containing a silyl ether linkage, a compoundrepresented by the formula (I)′ is preferred:

in which Z is a hydrogen atom or an alkyl group having 1-4 carbon atoms;X is a group represented by the formula (I-I), in which R^(a) is alinear or branched alkylene group having 1-5 carbon atoms, and each ofR^(b), R^(c) and R^(d) independently is a linear or branched alkyl grouphaving 1-5 carbon atoms; and Y is a linear or branched alkyl grouphaving 1-8 carbon atoms or a group represented by the formula (I-I), inwhich R^(a) is a linear or branched alkylene group having 1-5 carbonatoms, and each of R^(b), R^(c) and R^(d) independently is a linear orbranched alkyl group having 1-5 carbon atoms.

As the copper complex of the invention, a compound represented by theformula (I) is preferred:

in which Z is a hydrogen atom or an alkyl group having 1-4 carbon atoms;X is a group represented by the formula (I-I), in which R^(a) is alinear or branched alkylene group having 1-5 carbon atoms, and each ofR^(b), R^(c) and R^(d) independently is a linear or branched alkyl grouphaving 1-5 carbon atoms; and Y is a linear or branched alkyl grouphaving 1-8 carbon atoms or a group represented by the formula (I-I), inwhich R^(a) is a linear or branched alkylene group having 1-5 carbonatoms, and each of R^(b), R^(c) and R^(d) independently is a linear orbranched alkyl group having 1-5 carbon atoms.

In the formulas, it is preferred that X is the same as Y. Y preferablyis a linear or branched alkyl group having 1-8 carbon atoms. R^(a)preferably is an alkylene group of 1-3 carbon atoms which may carry oneor more alkyl substituents. Particularly preferred is that Z is hydrogenand each of R^(b), R^(c) and R^(d) is methyl.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a schematic view of a CVD system which can be employed for thecopper thin film production, wherein 1 denotes a glass ampul, 2 denotesa heater (vaporizer), 3 denotes a reactor, 4 denotes a heater (reactor),5 denotes a trap, 6 denotes a heater (for pre-heating), 7 denotes asubstrate, and 8 denotes a copper complex source.

DETAILED DESCRIPTION OF INVENTION

In the invention, examples of the β-diketonato ligands containing asilyl ether linkage include the compounds of the following formulas(III)′ to (XIV)′:

The above-illustrated β-diketone compounds can be obtained according tothe below-illustrated scheme, in which a silylated ketone is reactedwith a silylated organic acid ester in the presence of a base, or asilylated organic acid ester is reacted with a ketone in the presence ofa base, and the reaction product is treated with an acid. Theacid-treated product was purified by distillation or columnchromatography. Other known processes also are utilizable.

The β-ketonato copper complex, i.e., a copper complex in which anenolate anion of β-diketone is coordinated to copper, can be obtained bya reaction between β-diketone and copper hydroxide (below-illustratedprocess 1 for copper complex synthesis) or a reaction between an enolateanion of β-diketone and a copper salt such as cupric chloride(below-illustrated process 2 for copper complex synthesis). Thesynthesis can be performed in most organic solvents such as hydrocarbons(e.g., hexane and toluene), ethers (e.g., tetrahydrofuran (THF) anddimethoxyethane), nitrites (e.g., acetonitrile), halogenatedhydrocarbons (e.g., dichloromethane), alcohols (e.g., isopropanol), andesters (e.g., ethyl acetate). Water produced in the process 1 can bedistilled off together the solvent (e.g., toluene) by azeotropicdistillation. When such a solvent as THF is used, water is removed fromthe reaction mixture by distillation under reduced pressure at roomtemperature together with the solvent. Otherwise, water can be removedusing a dehydrating agent such as anhydrous sodium sulfate, anhydrousmagnesium sulfate, anhydrous copper sulfate, molecular sieves, ornonionic water-absorbing polymer.[Process 1 for Copper Complex Synthesis]

[Process 2 for Copper Complex Synthesis]

The produced copper complex can be purified by column chromatographyusing commercially available silica gel for chromatography or adehydrated silica gel which is prepared by dehydrating the commerciallyavailable silica gel, or by distillation, or by their combination.

An example of the copper complex having the silylether type β-diketonatoligand is represented by the following formula (III):

The copper complex of the formula (III) is a copper complex having aβ-diketone enolate anion ligand of the aforementioned formula (III)′which corresponds a compound of the aforementioned formula (I) in whichX is (CH₃)₃SiO—C(CH₃)₂—, Y is (CH₃)₃C—, and Z is H, namely,bis-(2,6,6-trimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)complex [hereinafter referred to as Cu(sobd)₂].

The β-diketones of the aforementioned formulas (IV)′ to (XIV)′ give thebelow-illustrated copper complexes (IV) to (XIV), respectively, whichhave an enolate anion of the corresponding β-diketone.

The copper complex of the invention can be employed for producing acopper-containing thin film by chemical vapor deposition in the knownCVD system as illustrated in FIG. 1.

The vaporization of the copper complex in the chemical vapor depositionprocess can be performed by directly supplying the copper complex into avaporization chamber, or by diluting the copper complex with anappropriate solvent (e.g., hexane, toluene, or tetrahydrofuran) andsupplying thus produced solution into a vaporization chamber.

The deposition on a substrate can be performed by the known CVD process.The copper complex is thermally decomposed under reduced pressure or inthe presence of an inert gas. Otherwise, the copper complex can bedecomposed and deposited in the presence of a reducing gas such ashydrogen gas. Also employable is a plasma CVD process using a hydrogengas to deposit metallic copper. Further, thermal decomposition or plasmaCVD of the copper complex in the presence of oxygen can be also employedfor deposition of a copper oxide thin film.

The invention is further illustrated by the following examples.

EXAMPLE 1

(1) Synthesis of 2,6-dimethyl-2,6-di(trimethylsilyloxy)-3,5-heptadione[Represented by the Formula (V)′, Hereinafter Referred to as “dsobd”]

In a 50 mL-volume flask were placed 1.80 g (45.0 mmol) of 60′ sodiumhydride and 9.83 g (51.7 mmol) of methyl2-(trimethylsilyloxy)-2-methyl-propionate. The resulting solution washeated to 120° C., and to the heated solution was dropwise added slowlya solution of 3.00 g (17.2 mmol) of2-(trimethylsilyloxy)-2-methyl-3-butanone in 9 mL of toluene. After thedropwise addition was complete, the reaction mixture was heated at 120°C. for one hour. Subsequently, the reaction mixture was cooled to roomtemperature and made weak acidic by the addition of an aceticacid-toluene mixture. The precipitated sodium acetate was removed byfiltration, to obtain a yellow solution.

The obtained solution was concentrated and purified by columnchromatography using dehydrated silica gel, to give 1.20 g (3.61 mmol,yield 21%) of the desired main product, i.e.,2,6-dimethyl-2,6-di(trimethylsilyloxy)-3,5-heptadione.

The product was identified by NMR, IR, and MS.

¹H-NMR (CDCl₃): δ 0.15 (s, 9H), 1.41 (s, 9H), 4.00 (s, 0.4H), 6.43 (s,0.8H), 15.55 (s, 0.8H)

IR (cm⁻¹): 2961, 1605(br), 1252, 1198, 1048, 842

MS (m/e): 332

(2) Preparation of Cu(dsobd)₂[bis(2,6-dimethyl-2,6-di(trimethylsilyloxy)-3,5-heptadionato) copper(II)Complex]

Since production of the desired β-diketone was confirmed in theabove-mentioned procedure, the desired copper complex was prepared byadding a copper source to a product prepared in the same manner.

In a 50 mL-volume flask were placed 1.80 g (45.0 mmol) of 60′ sodiumhydride and 9.83 g (51.7 mmol) of methyl2-(trimethylsilyloxy)-2-methyl-propionate. The resulting solution washeated to 120° C., and to the heated solution was dropwise added slowlya solution of 3.00 g (17.2 mmol) of2-(trimethylsilyloxy)-2-methyl-3-butanone in 9 mL of toluene. After thedropwise addition was complete, the reaction mixture was heated at 120°C. for one hour. Subsequently, the reaction mixture was cooled to 30° C.There was produced 1.28 g (3.61 g) of2,6-dimethyl-2,6-di(trimethylsilyloxy)-3,5-heptadionato sodium salt. Tothe reaction solution was added 0.24 g (1.78 mmol) of cupric chloride.The reaction solution was immediately turned to dark green. The solutionwas continuously stirred at 80° C. for 2 hours and cooled to roomtemperature. Then, the reaction solution was washed with water. Theobtained organic portion was dried, and purified by columnchromatography using dehydrated silica gel, to give 1.10 g (1.52 mmol,yield 85%, based on the amount of cupric chloride) ofbis(2,6-dimethyl-2,6-di(trimethylsilyloxy)-3,5-heptadionato) copper(II)complex.

The product was identified by IR and elemental analysis.

IR (cm⁻¹): 2978, 1567, 1498, 1414, 1252, 1197, 1045,

Elemental analysis for C₃₀H₆₂O₈Si₄Cu

Found: C 49.0%, H 8.99%, Cu 8.6%.

Calculated: C 49.6%, H 8.60%, Cu 8.74.

In the IR spectrum, a peak of 1,605 cm⁻¹ assignable to β-diketonedisappeared, and a peak of 1,567 cm⁻¹ assignable to diketonato wasobserved. Accordingly, it was confirmed that the desired copper complexwas produced. This copper complex is a new compound.

EXAMPLE 2

(1) Synthesis of 2,6,6-trimethyl-2-(trimethylsilyloxy)-3,5-heptadione[Represented by the Formula (III)′, Hereinafter Referred to as “sobd”]

In a 50 mL-volume flask, 0.40 g (10.3 mmol) of sodium amide and 1.20 g(12.0 mmol) of pinacolin were suspended in 3 mL of toluene, and theresulting suspension was stirred for 30 min. at room temperature.Subsequently, a solution of 1.00 g (5.25 mmol) of methyl2-(trimethylsilyloxy)-2-methyl-propionate in 6 mL of toluene wasdropwise added slowly. After the dropwise addition was complete, themixture was subjected to reaction for one hour at room temperature. Thereaction mixture was then made weak acidic with an acetic acid-toluenemixture. The precipitated sodium acetate was removed by filtration togive a yellow solution.

The obtained solution was concentrated and purified by columnchromatography using dehydrated silica gel, to give 0.83 g (3.21 mmol,yield 61%) of the desired main product, i.e.,2,6,6-trimethyl-2-(trimethylsilyloxy)-3,5-heptadione.

The product was identified by NMR, IR, and MS.

¹H-NMR (CDCl₃): δ 0.14 (s, 9H), 1.17 (s, 9H), 1.39 (s, 6H), 3.86 (s,0.3H), 6.09 (s, 0.85H), 15.72 (s, 0.85H)

IR (cm⁻¹) 2966, 1600(br), 1252, 1197, 1045, 841

MS (m/e) 258

(2) Preparation of Cu(sobd)₂[bis(2,6,6-trimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)Complex, Represented by the Formula (III)]

Since production of the desired β-diketone was confirmed in theabove-mentioned procedure, the desired copper complex was prepared byadding a copper source to a product prepared in the same manner.

In a 50 mL-volume flask, 0.40 g (10.3 mmol) of sodium amide and 1.20 g(12.0 mmol) of pinacolin were suspended in 3 mL of toluene, and theresulting suspension was stirred for 30 min. at room temperature.Subsequently, a solution of 1.00 g (5.25 mmol) of methyl2-(trimethylsilyloxy)-2-methyl-propionate in 6 mL of toluene wasdropwise added slowly. After the dropwise addition was complete, themixture was subjected to reaction for one hour at room temperature. Tothe reaction solution was added 0.22 g (1.60 mmol) of cupric chloride.The reaction solution immediately turned to dark green. The solution wascontinuously stirred for one hour at room temperature. Then, thereaction solution was washed with water. The obtained organic portionwas dried, and purified by column chromatography using dehydrated silicagel, to give 0.80 g (1.38 mmol, yield 86%, based on the amount of cupricchloride) of bis(2,6,6-trimethyl-2-(trimethylsilyloxy)-3,5-heptadionato)copper(II) complex.

The product was identified by IR and elemental analysis.

IR (cm⁻¹) 2960, 1561, 1501, 1412, 1252, 1196, 1047,

Elemental analysis for C₂₆H₅₀O₆Si₂Cu

Found: C 54.8%, H 8.20%, Cu 11%.

Calculated: C 54.0%, H 8.71%, Cu 11.0.

In the IR spectrum, a peak of 1,600 cm⁻¹ assignable to β-diketonedisappeared, and a peak of 1,561 cm⁻¹ assignable to diketonato wasobserved. This copper complex is a new compound.

EXAMPLE 3

(1) Synthesis of 2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione[Represented by the Formula (VIII)′, Hereinafter Referred to as “sopd”]

In a 50 ml-volume flask, 0.50 g (12.8 mmol) of sodium amide and 0.45 g(5.22 mmol) of 3-methyl-2-butanone were suspended in 1.5 g of hexane,and the resulting suspension was stirred at 15° C. for 30 min.Subsequently, a solution of 1.20 g (6.31 mmol) of methyl2-(trimethylsilyloxy)-2-methyl-propionate in 3 g of hexane was dropwiseadded slowly. After the dropwise addition was complete, the mixture wassubjected to reaction at 15° C. for one hour. The reaction mixture wasthen made weak acidic with an acetic acid-toluene mixture. Theprecipitated sodium acetate was removed by filtration to give a yellowsolution.

The obtained solution was concentrated and purified by columnchromatography using dehydrated silica gel, to give 0.91 g (3.71 mmol,yield 71′) of the desired main product, i.e.,2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione.

The product was identified by NMR, IR, and MS.

¹H-NMR (CDCl₃): δ 0.14 (s, 9H), 1.14 (s, 6H), 1.39 (s, 6H), 2.44-2.50(m, 0.85H), 2.64-2.69 (m, 0.15H), 3.77 (s, 0.3H), 5.97 (s, 0.85H), 15.51(s, 0.85H)

IR (cm⁻¹) 2971, 1606(br), 1253, 1199, 1045, 842

MS (m/e): 244

(2) Preparation of Cu(sopd)₂[bis(2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)Complex, Represented by the Formula (VIII)]

Since production of the desired β-diketone was confirmed in theabove-mentioned procedure, the desired copper complex was prepared byadding a copper source to a product prepared in the same manner.

In a 50 mL-volume flask, 0.50 g (12.8 mmol) of sodium amide and 0.45 g(5.22 mmol) of 3-methyl-2-butanone were suspended in 1.5 g of hexane,and the resulting suspension was stirred at 15° C. for 30 min.Subsequently, a solution of 1.20 g (6.31 mmol) of methyl2-(trimethylsilyloxy)-2-methyl-propionate in 3 g of hexane was drop-wiseadded slowly. After the dropwise addition was complete, the mixture wassubjected to reaction at 15° C. for one hour. To the reaction solutionwas added 0.25 g (1.86 mmol) of cupric chloride. The reaction solutionwas immediately turned to dark green. The solution was continuouslystirred for one hour at room temperature. Then, the reaction solutionwas washed with water. The obtained organic portion was dried, andpurified by column chromatography using dehydrated silica gel, to give0.86 g (1.56 mmol, yield 84%, based on the amount of cupric chloride) ofbis(2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)complex.

The product was identified by IR and elemental analysis.

IR (cm⁻¹): 2965, 1592, 1501, 1428, 1252, 1199, 1044,

Elemental analysis for C₂₄H₄₆O₆Si₂Cu

Found: C 53.2%, H 8.53%, Cu 11%.

Calculated: C 52.4%, H 8.42%, Cu 11.5%.

In the IR spectrum, a peak of 1,606 cm⁻¹ assignable to β-diketonedisappeared, and a peak of 1,592 cm⁻¹ assignable to diketonato wasobserved. This copper complex is a new compound.

EXAMPLE 4

(1) Synthesis of sopd by Different Process

In a 50 mL-volume flask, 13.7 g (0.351 mol) of sodium amide wassuspended in 200 mL of hexane and then 26.7 g (0.140 mol) of methyl2-(trimethylsilyloxy)-2-methylpropionate was added. To the resultingsolution was dropwise added 12.1 g (0.141 mol) of 3-methyl-2-butanone,and the mixture was kept at 15° C. In the development of reaction,production of gaseous ammonia was observed. The reaction was continuedat 15° C. for one hour. The reaction solution was then made weak acidicwith acetic acid. The obtained hexane portion was washed with water anddried over anhydrous sodium sulfate. The dried portion was distilled at101° C./8 mmHg, to give 18.8 g (0.770 mol, yield 55%) of the desired2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione.

The product was identified by NMR, IR, and MS.

H-NMR (CDCl₃): δ 0.14 (s, 9H), 1.14 (s, 6H), 1.39 (s, 6H), 2.44-2.50 (m,0.85H), 2.64-2.69 (m, 0.15H), 3.77 (s, 0.3H), 5.97 (s, 0.85H), 15.51 (s,0.85H)

IR (cm⁻¹): 2971, 1606(br), 1253, 1199, 1045, 842

MS (m/e): 244

In the below-described (2-1) to (2-3), a copper complex of Cu(sopd)₂ wasprepared by three different processes.

(2-1) Preparation of Cu(sopd)₂ by Azeotropic Toluene DistillationDehydration

In 100 mL-volume flask were placed 4.43 g (45.4 mmol) of copperhydroxide, 22.2 g (90.8 mmol) of2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione, and 50 mL of toluene.The resulting mixture was heated to 130° C., and water produced byreaction was dehydrated by azeotropic toluene distillation. The amountof the produced and distilled water was confirmed by receiving andmeasuring it in a water receiver. The reaction was complete withinapprox. one hour. The obtained dark green solution was filtered and thefiltrate was concentrated to give a viscous dark green solution. Thesolution was distilled at 179° C./0.5 Torr to give 20.2 g (36.8 mmol,yield 81%) of the desired copper complex, namely,bis-(2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)complex.

(2-2) Preparation of Cu(sopd)₂ at Room Temperature in THF Solvent

The desired Cu(sopd)₂ can be prepared by reacting2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione with copper(II)hydroxide in an organic solvent such as ether, acetonitrile, alcohol,ketone, ester, or hydrocarbon at room temperature. The following is apreparing procedure in a THF solvent.

In 100 mL-volume flask were placed 4.50 g (46.2 mmol) of copperhydroxide, 22.6 g (92.3 mmol) of2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione, and 50 mL of THF. Theresulting mixture was stirred for one hour at room temperature in theabsence of a dehydrating agent. The resulting dark blue solution wasfiltered, and the THF solvent was distilled off to leave a viscous darkgreen solution. The solution was distilled at 179° C./0.5 Torr to give21.1 g (38.3 mmol, yield 83%) of the desired copper complex, namely,bis(2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)complex.

(2-3) Preparation of Cu(sopd)₂ at Room Temperature in DimethoxyethaneSolvent

The preparation in dimethoxyethane solvent is described below.

In 50 mL-volume flask were placed 1.10 g (11.3 mmol) of copperhydroxide, 5.00 g (20.5 mmol) of2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadione, and 15 mL ofdimethoxyethane. The resulting mixture was stirred for 2 hours at roomtemperature in the absence of a dehydrating agent. The resulting darkblue solution was filtered, and the dimethoxyethane solvent wasdistilled to leave a viscous dark green solution. The solution wasdistilled at 179° C./0.5 Torr to give 4.57 g (8.30 mmol, yield 81%) ofthe desired copper complex, namely,bis(2,6-dimethyl-2-(trimethylsilyloxy)-3,5-heptadionato) copper(II)complex.

The copper complex produced in (2-3) above was identified by IR andelemental analysis.

IR (cm⁻¹): 3458(br), 2963, 1568, 1518, 1422, 1251, 1196, 1035, 889, 841

Elemental analysis for C₂₄H₄₆O₆Si₂Cu

Found: C 53.0%, H 8.39%, Cu 11.5.

Calculated: C 52.4%, H 8.42%, Cu 11.5%.

M.p.: 62° C.

The products of (2-1) and (2-2) showed almost same elemental analysisdata.

In the IR spectrum, a peak of 1,606 cm¹ assignable to β-diketonedisappeared, and a peak of 1,568 cm⁻¹ assignable to diketonato wasobserved. The broad peak observed in the vicinity of 3,400 cm⁻¹ isassignable to a water of crystallization coordinated to the coppercomplex. This broad peak was not observed when the product was examinedjust after the distillation, namely under good conditions.

(3) Vapor Deposition Test

The copper complex of Cu(sopd)₂ [represented by the formula (VIII)]prepared in Example 3 was subjected to vapor deposition test accordingto CVD process, to examine its film forming property. For comparison,the same vapor deposition test was performed usingbis(6-ethyl-2,2-dimethyl-3,5-decandionato) copper complex of theaforementioned formula (II).

The test was performed using the apparatus illustrated in FIG. 1. Thecopper complex 8 placed in a vaporizer (glass ample) 1 was heated by aheater 2 for vaporization. The vaporized complex came out of thevaporizer together with helium gas. The gas coming out of the vaporizerjoined a pre-heated hydrogen gas supplied through the hydrogen gas line,and entered the reactor 3. The center portion of the glass reactor couldbe heated by the heater 4. The copper complex introduced into thereactor reductively decomposed and produced a metallic copper on asurface of a substrate 7 which was set at the center part and heated tothe predetermined temperature in a reducing atmosphere. The gas comingout of the reactor was exhausted to atmospheric air through the trap 5.

The copper film-formation depends on the vapor deposition conditionssuch as the copper complex vaporization temperature and the substratetemperature.

Table 1 shows the vapor deposition conditions employed in the test andthe results of film formation. The substrate is a rectangular substrateof 7 mm×4 mm. TABLE 1 Example 3: copper complex - Cu(sopd)₂ Condition ofvapor deposition Vaporization temperature: 140° C. Substrate:Ta—N/SiO₂/Si Substrate temperature: 230° C. Vaporization period: 60 min.Pressure in the reaction system: atmospheric H₂ flow rate: 36 mL/min. Heflow rate:  5 mL/min. Characteristics of formed film Film thickness: 200nm Specific resistance: 4.5 μΩ cm Appearance: Smooth glossy metalsurface Comparison Example 1: copper complex - bis(6-ethyl-2,2-dimethyl-3,5-decandionato) copper complex Condition of vapor depositionVaporization temperature: 140° C. Substrate: Ta—N/SiO₂/Si Substratetemperature: 250° C. Vaporization period: 60 min. Pressure in thereaction system: atmospheric H₂ flow rate: 36 mL/min. He flow rate:  5mL/min. Characteristics of formed film Almost no film is produced.

The above-mentioned results indicate that the Cu(sopd)₂ of the inventionshows an excellent film-forming property, as compared with thepreviously known copper complex.

Industrial Utility

The copper complex of the invention is a divalent copper complex whichis thermally stable, as compared with the thermally unstable monovalentcopper complex, and is resistant to thermal decomposition in thevaporizer. Accordingly, it is advantageously employable for industriallypreparing a copper-containing film by chemical vapor deposition.Further, the copper complex of the invention can produce a film at arate greater than that shown by the previously known divalent coppercomplex. This means that the copper complex of the invention ispractically advantageous, and that the copper complex of the inventionis favorably employable for the preparation of a copper film widelygreatly utilized as the circuit material of semiconductors.

1. A divalent copper complex having β-diketonato ligands containing asilyl ether linkage.
 2. The copper complex of claim 1, wherein theβ-diketonato ligands containing a silyl ether linkage is represented bythe formula (I)′:

in which Z is a hydrogen atom or an alkyl group having 1-4 carbon atoms;X is a group represented by the formula (I-I), in which R^(a) is alinear or branched alkylene group having 1-5 carbon atoms, and each ofR^(b), R^(c) and R^(d) independently is a linear or branched alkyl grouphaving 1-5 carbon atoms; and Y is a linear or branched alkyl grouphaving 1-8 carbon atoms or a group represented by the formula (I-I), inwhich R^(a) is a linear or branched alkylene group having 1-5 carbonatoms, and each of R^(b), R^(c) and R^(d) independently is a linear orbranched alkyl group having 1-5 carbon atoms.
 3. The copper complex ofclaim 1, which is represented by the formula (I):

in which Z is a hydrogen atom or an alkyl group having 1-4 carbon atoms;X is a group represented by the formula (I-I), in which R^(a) is alinear or branched alkylene group having 1-5 carbon atoms, and each ofRb, Rc and Rd independently is a linear or branched alkyl group having1-5 carbon atoms; and Y is a linear or branched alkyl group having 1-8carbon atoms or a group represented by the formula (I-I), in which R^(a)is a linear or branched alkylene group having 1-5 carbon atoms, and eachof R^(b), R^(c) and R^(d) independently is a linear or branched alkylgroup having 1-5 carbon atoms.
 4. The copper complex of claim 2, whereinY is the same as X.
 5. The copper complex of claim 3, wherein Y is thesame as X.
 6. The copper complex of claim 2, wherein Y is a linear orbranched alkyl group having 1-8 carbon atoms.
 7. The copper complex ofclaim 3, wherein Y is a linear or branched alkyl group having 1-8 carbonatoms.
 8. The copper complex of claim 2, wherein R^(a) is an alkylenegroup having 1-3 carbon atoms which can have one or more alkylsubstituent.
 9. The copper complex of claim 3, wherein R^(a) is analkylene group having 1-3 carbon atoms which can have one or more alkylsubstituent.
 10. The copper complex of claim 2, wherein Z is a hydrogenatom, and each of R^(b), R^(c) and R^(d) is methyl.
 11. The coppercomplex of claim 3, wherein Z is a hydrogen atom, and each of R^(b),R^(c) and R^(d) is methyl.
 12. A method of forming a copper-containingfilm by chemical vapor deposition using a copper complex of claim 1 as acopper source.
 13. A method of forming a copper-containing film bychemical vapor deposition using a copper complex of claim 2 as a coppersource.
 14. A method of forming a copper-containing film by chemicalvapor deposition using a copper complex of claim 3 as a copper source.